Gas barrier film and photoelectric conversion device

Abstract

Provided are: a gas barrier film which has high barrier properties and high light intake efficiency; and a photoelectric conversion device which has a long life and excellent photoelectric conversion efficiency. According to an embodiment, a gas barrier film including a gas barrier layer is provided. The gas barrier layer includes one or more multilayer films including a translucent first layer and a silicon nitride film adjacent to the first layer. The first layer is located on one main surface of the gas barrier layer, and the silicon nitride film is located on the other main surface of the gas barrier layer. The refractive index of the gas barrier layer increases from the main surface side where the first layer is located toward the other main surface side.

Description

Technical Field

[0001] Embodiments of the present invention relate to gas barrier films and photoelectric conversion devices. Background Technology

[0002] Gas barriers are widely used in electronic devices, packaging, and other applications. For example, water vapor barriers are used in perovskite solar cells, organic electroluminescent (organic EL) devices, and non-aqueous electrolyte batteries. In food or pharmaceutical packaging, oxygen barriers are used to prevent spoilage of the contents.

[0003] As barrier films, there are known films comprising barrier layers formed on a substrate by vacuum deposition such as atomic layer deposition (ALD) or chemical vapor deposition (CVD), and films comprising barrier layers formed by coating a substrate with a solution containing a silicon compound such as polysilazane, followed by modification treatment of the coating by vacuum ultraviolet (VUV) irradiation. Furthermore, it is known to form multilayer structures by overlapping multiple barrier layers. For example, a barrier film has been reported to be formed by forming a barrier layer on a substrate by CVD, coating a solution of a silicon compound on it, and then modifying it by VUV treatment to form other barrier layers.

[0004] Vacuum film deposition equipment such as CVD is expensive and time-consuming, resulting in low productivity. Furthermore, in chemical vapor deposition, the coverage of particles on the substrate is poor, leading to defects at particle locations and thus low barrier properties in the resulting barrier layer. Regarding the modification of polysilazane, treatment in an oxygen environment produces a silicon oxide film (SiOx (x>0) film), while treatment in a nitrogen environment produces a silicon nitride film (SiNx (x>0) film). It has been reported that SiOx films obtained through coating and vacuum modification offer good barrier properties, but SiNx films obtained through coating and vacuum modification can achieve even higher performance with a thickness of less than 10. -5 g / m 2 Ultra-high barrier properties of d (grams per square meter per day). Summary of the Invention

[0005] This invention provides a gas barrier film with high barrier properties and high light capture efficiency, as well as a photoelectric conversion device with long life and excellent photoelectric conversion efficiency.

[0006] According to an embodiment, a gas barrier film including a gas barrier layer is provided. The gas barrier layer includes one or more multilayer films, each multilayer film including a light-transmitting first layer and a silicon nitride film adjacent to the first layer. The first layer is located on one main surface of the gas barrier layer, and the silicon nitride film is located on another main surface of the gas barrier layer. The refractive index of the gas barrier layer increases from the main surface side where the first layer is located towards the other main surface side.

[0007] Furthermore, according to an embodiment, a photoelectric conversion device is provided, comprising a light-transmitting first electrode, a second electrode, a photoelectric conversion layer, and a barrier film as described in the above embodiment. The photoelectric conversion layer is located between the first electrode and the second electrode. The first electrode is adjacent to the barrier layer on the other main surface side where the silicon nitride film is located.

[0008] According to other embodiments, a photoelectric conversion device comprising a second electrode, a photoelectric conversion layer, and a gas barrier film is provided. The gas barrier film is a further included, in the above-described embodiments, a transparent electrode adjacent to the gas barrier layer on the other main surface side where the silicon nitride film is located. The photoelectric conversion layer is located between the transparent electrode and the second electrode.

[0009] The aforementioned gas-barrier film exhibits high barrier properties and high light capture efficiency. Therefore, it can provide a photoelectric conversion device with long lifespan and excellent photoelectric conversion efficiency. Attached Figure Description

[0010] Figure 1 This is a conceptual diagram representing Snell's Law.

[0011] Figure 2 This is a schematic cross-sectional view showing a first example of a gas barrier membrane according to an embodiment.

[0012] Figure 3 This is a schematic cross-sectional view showing a second example of the gas barrier membrane of the embodiment.

[0013] Figure 4 This is a schematic cross-sectional view showing a third example of the gas barrier membrane according to the embodiment.

[0014] Figure 5 This is a schematic cross-sectional view showing a fourth example of the gas barrier membrane according to the embodiment.

[0015] Figure 6 This is a schematic cross-sectional view showing a first example of a solar cell device according to an embodiment.

[0016] Figure 7 This is a schematic cross-sectional view showing a second example of a solar cell device according to an embodiment.

[0017] Explanation of reference numerals in the attached figures

[0018] 1, 6, 8, 9…Gas barrier film, 2…Substrate, 2a, 2b…Surface (main surface), 3…Multilayer film, 3a, 3b…Surface (main surface), 4…First layer, 5…Silicon nitride film, 7…Second layer, 12…Transparent electrode, 13…Hole transport layer, 14…Photoelectric conversion layer, 15…Electron transport layer, 16…Cathode, 17…Adhesive layer, 18…Backsheet, 19…First direction, 20, 21…Solar cell device, 100…Interface, 101, 102…Dielectric, 111…Incident light, 112…Outgoing light, 113…Reflected light. Detailed Implementation

[0019] (First Implementation)

[0020] According to a first embodiment, a gas barrier film is provided. The gas barrier film includes a gas barrier layer comprising one or more multilayer films, each multilayer film including a light-transmitting first layer and an adjacent silicon nitride film (SiNx (x>0) film). The light-transmitting first layer is located on one principal surface of the gas barrier layer, and the silicon nitride film is located on another principal surface. The refractive index of the gas barrier layer increases from the principal surface side where the first layer is located towards the other principal surface side.

[0021] Both the first gas barrier layer and the silicon nitride film constituting the gas barrier film exhibit light transmittance. A gradual increase in refractive index exists from one principal surface side of the gas barrier layer towards the other principal surface side. For example... Figure 1 Snell's law (relative refractive index n) represents its concept. 12 As shown in the diagram (n2 / n1 = sinα / sinβ), at the interface 100 between the low-refractive-index medium 101 and the high-refractive-index medium 102, the exit angle β of the emitted light 112 is smaller than the incident angle α of the incident light 111 that is transmitted from medium 101 to medium 102 and incident onto the interface 100. Furthermore, the reflection angle γ of the reflected light 113 is equal to the incident angle α. In the gas-barrier film according to the first embodiment, due to the gradual change in refractive index within the gas-barrier layer, the direction of the emitted light from the high-refractive-index main surface is closer to being perpendicular to the main surface of the gas-barrier layer than the direction of the incident light incident onto the low-refractive-index main surface. That is, light irradiating the gas-barrier film from various directions can be emitted from the back side with consistent direction. Thus, the gas-barrier film can efficiently capture light. Therefore, for example, when the gas-barrier film is applied to light-utilizing devices such as solar cell devices, the efficiency of light capture into the device can be improved.

[0022] The gas barrier film can be a gas barrier film with a transparent electrode. The transparent electrode, for example, is adjacent to the gas barrier layer on the main surface where the silicon nitride film in the gas barrier layer is located. By providing a transparent electrode on the main surface of the gas barrier layer with a high refractive index, the efficiency of light harvesting into the device can be improved when this transparent electrode is used as an electrode in a photoelectric conversion device such as a solar cell. Preferably, the transparent electrode has a refractive index greater than or equal to the maximum refractive index in the gas barrier layer. Further extending the gradient of the refractive index in the gas barrier layer to the transparent electrode further increases the light harvesting efficiency.

[0023] The gas barrier film may further comprise a substrate having a film shape. The first layer described above, for example, is disposed on the surface of the substrate and can function as a planarization film. The substrate is also made of a light-transmitting material.

[0024] Reference Figures 2-5 Examples of gas barrier films according to embodiments will be described. The gas barrier films shown in each figure include a substrate. The gas barrier layer of the gas barrier film shown in each figure comprises a multilayer film including a first layer and a silicon nitride film. In each figure, the thickness direction of the gas barrier film is parallel to the z-axis direction. The surface direction of the gas barrier film is parallel to a plane defined by the x-axis and y-axis directions. The x-axis, y-axis, and z-axis directions intersect each other perpendicularly. Furthermore, in each figure, components that appear in multiple figures are labeled with the same reference numerals, and descriptions are omitted.

[0025] Figure 2 The illustrated gas barrier film 1 comprises a substrate 2 and a multilayer film 3 serving as a gas barrier layer. The multilayer film 3 comprises a first layer 4 and a silicon nitride film 5. The substrate 2 has a layer shape or a film shape. Regarding the substrate 2, two surfaces intersecting the thickness direction (z-axis direction) are designated as principal surfaces (main surfaces) 2a and 2b. Each surface 2a and 2b is parallel to the xy plane. Alternatively, it can be said that the other surface 2b is located on the opposite side of surface 2a. The substrate 2 is transparent. Furthermore, the substrate 2 is formed, for example, from polyethylene terephthalate (PET), polycarbonate, ethylene tetrafluoroethylene (ETFE), polyimide (PI), polyethylene naphthalate (PEN), etc.

[0026] The multilayer film 3 is disposed on one side of the substrate 2. Figure 2 In this case, the multilayer film 3 is stacked on one surface 2a of the substrate 2. The multilayer film 3 has barrier properties against gases such as water vapor and oxygen. The multilayer film 3 is substantially composed, for example, of a first layer 4 as a planarization film and a silicon nitride film 5. The two surfaces of the first layer 4 and the silicon nitride film 5 that intersect the thickness direction (z-axis direction) are designated as principal surfaces (main surfaces). Regarding the multilayer film 3 (gas barrier layer), the two surfaces that intersect the thickness direction (z-axis direction) are designated as principal surfaces (main surfaces) 3a and 3b.

[0027] A light-transmitting first layer 4 is disposed on one surface 2a of the substrate 2. The first layer 4 can be selected from the group consisting of an organosilicon compound film, a silicon oxide film (SiOx (x>0) film), an organic-inorganic hybrid film, and an organic film. The first layer 4 is obtained, for example, by coating a coating agent containing the material of the aforementioned film onto one surface 2a of the substrate 2 and drying it. The silicon oxide film can also be obtained, for example, by modifying an organosilicon compound film or a polysilazane compound film with vacuum ultraviolet light in an O2 environment. That is, the silicon oxide film can be a silicon oxide film modified from an organosilicon compound or a silicon oxide film modified from a polysilazane compound. As a specific example of the latter, a film obtained by a method comprising: coating a solution of perhydropolysilazane (PHPS) onto the substrate 2, for example by spin coating, removing the solvent by pre-baking, for example, and then irradiating it with vacuum ultraviolet light (VUV) in an O2 environment. An example of the reaction that generates a SiOx film by irradiating a PHPS-coated solution, formed by drying it under O2 at room temperature, with vacuum ultraviolet light at a wavelength of 172 nm is shown in the following chemical formula 1. As shown in chemical formula 1, Si-O bonds are formed to generate SiOx, resulting in the release of NH3. Silicon oxide films can also be obtained by modifying films of organosilicon compounds and polysilazane compounds by heating under O2 conditions instead of using vacuum ultraviolet light modification.

[0028]

Chemical Formula 1

[0029]

[0030] Since the PHPS film is formed on the substrate 2 by coating, a flat surface can be obtained even if the substrate 2 has unevenness due to the presence of particles or the like. Therefore, the first layer 4 serves as a planarization film. In addition, if the PHPS film is formed by coating, the manufacturing cost of the film can be reduced.

[0031] A silicon nitride film 5 is disposed on the surface of the first layer 4 parallel to the xy plane. The silicon nitride film 5 is obtained, for example, by modifying a polysilazane compound film using vacuum ultraviolet light under N2 environment. Specifically, it can be obtained by a method including the following steps: coating a solution of PHPS onto the first layer 4, for example, by spin coating; removing the solvent, for example, by pre-baking; and then irradiating it with vacuum ultraviolet light under N2 environment. An example of a reaction in which a SiNx film is generated by irradiating a PHPS film formed by coating and drying a PHPS solution at room temperature under N2 environment with vacuum ultraviolet light at a wavelength of 172 nm is shown in the following chemical formula 2. As shown in chemical formula 2, Si-N bonds are formed to generate SiNx, resulting in the release of H2.

[0032] [Chemical Formula 2]

[0033]

[0034] The silicon nitride film 5 obtained through modification treatment has a refractive index that varies along the thickness direction (e.g., the z-axis direction) of the barrier film. Vacuum ultraviolet light primarily modifies the vicinity of the film's surface, thus the SiNation reaction occurs continuously from the surface towards the first layer 4. Therefore, the silicon nitride film 5 exhibits a gradual increase in silicon nitride concentration on the surface side (the main surface 3b side of the multilayer film 3) compared to the first layer 4 side. Consequently, the silicon nitride film 5 is characterized by a refractive index that increases from the first layer 4 side towards the surface side.

[0035] The refractive index of the silicon nitride film 5 is greater than that of the first layer 4. Since the exit angle (β) is smaller than the incident angle (α) of light transmitted from the first layer 4 at the interface between the first layer 4 and the silicon nitride film 5 to the silicon nitride film 5, light is introduced into the silicon nitride film 5 with its direction of travel nearly perpendicular to the principal surfaces 3a and 3b of the multilayer film 3. Furthermore, at its leading edge, the refractive index of the silicon nitride film 5 increases towards the principal surface 3b of the multilayer film 3. That is, throughout the entire multilayer film 3, the refractive index increases from the principal surface 3a on the substrate 2 side towards the principal surface 3b on its back side. Therefore, light entering the multilayer film 3 from the principal surface 3a on the substrate 2 side at various angles converges and exits on the back side in a direction nearly perpendicular to the principal surface 3b.

[0036] In a specific example of a gas barrier film, the minimum refractive index of the silicon nitride film 5 is 1.54, and the maximum refractive index of the silicon nitride film 5 is 1.7. For example, the refractive index can vary from 1.54 to 1.7 from the interface side with the light-transmitting first layer 4 to the back side side of the silicon nitride film 5. According to another example, the refractive index of the gas barrier layer increases from 1.4 to 1.7 from the principal surface side where the first layer is located to the other principal surface side.

[0037] The gas barrier layer may comprise multiple multilayer films 3 formed by a first layer 4 and a silicon nitride film 5. For example, multiple first layers and multiple silicon nitride films can be alternately arranged to form the gas barrier layer. However, the refractive index of the first layer located on one main side of the gas barrier layer becomes the smallest, and the refractive index of the silicon nitride film on the back main side becomes the largest, and care should be taken to ensure that the refractive index increases sequentially between them. For example, the refractive index of the silicon nitride film contained in the multilayer film located on one main side of the gas barrier layer may be 1.54, and the refractive index of the silicon nitride film contained in the multilayer film located on the other main side of the gas barrier layer may be 1.7.

[0038] Figure 2The gas barrier film 1 shown exhibits excellent barrier performance against gases such as water vapor and oxygen. Furthermore, the gas barrier film 1 is visible light transmittance and can efficiently capture light. Moreover, the multilayer film 3 includes a first layer 4 in addition to the silicon nitride film 5, so even if the thickness of the first layer 4 and the silicon nitride film 5 is reduced, sufficient barrier function can still be obtained. As a result, defects such as cracking of the first layer 4 and the silicon nitride film 5 can be avoided. The silicon nitride film 5 exhibits a certain barrier performance even when used alone. However, if the silicon nitride film is thickened, it is prone to cracking, so it is difficult to improve the barrier performance by thickening the silicon nitride film 5. By using the multilayer film 3, formed by overlapping the first layer 4 and the silicon nitride film 5, as the gas barrier layer, superior barrier performance can be exhibited compared to the silicon nitride film 5 alone.

[0039] Next, regarding Figure 3 The gas barrier membrane shown is explained below. Figure 3 The gas barrier film 6 shown comprises a substrate 2, a multilayer film 3, and a second layer 7. Details of the substrate 2 and the multilayer film 3 are as follows... Figure 2 As explained in the text.

[0040] The second layer 7 is disposed on the other side of the substrate 2. Figure 3 In this case, the second layer 7 is laminated on the other side 2b of the substrate 2. The second layer 7 is transparent. The second layer 7 can mitigate the stress difference between the stress applied to one side 2a of the substrate 2 and the stress applied to the other side 2b of the substrate 2. Therefore, the second layer 7 can suppress warping of the substrate 2 due to the stress difference. The second layer 7 is formed, for example, from the same material as the first layer 4. That is, the transparent second layer 7 can also be selected from the group consisting of organosilicon compound films, silicon oxide films (e.g., silicon oxide films obtained by modifying organosilicon compounds, silicon oxide films obtained by modifying polysilazane compounds), organic-inorganic hybrid films, and organic films.

[0041] Figure 3 The gas barrier film 6 shown exhibits excellent barrier performance against gases such as water vapor and oxygen. Furthermore, the gas barrier film 6 is visible light transmittant and can efficiently capture light. This gas barrier film 6 has a first layer 4 of a multilayer film 3 disposed on one side of the substrate 2, and a second layer 7 disposed on the other side of the substrate 2. As a result, the stress difference applied to one side of the substrate 2 and the stress applied to the other side can be reduced, thus suppressing warping of the substrate 2.

[0042] It should be noted that, Figure 3 The example described is that the first layer 4 and the second layer 7 are directly laminated on the two sides of the substrate 2, but it is not limited to this. Other layers such as adhesive layers can also be sandwiched between the substrate 2 and the first layer 4 or the second layer 7.

[0043] Next, regarding Figure 4 The gas barrier membrane shown is explained below. Figure 4The transparent electrode-supported gas barrier film 8 shown comprises a substrate 2, a multilayer film 3, and a transparent electrode 12. Details of the substrate 2 and the multilayer film 3 are as follows... Figure 2 As explained in the text.

[0044] A transparent electrode 12 is disposed on the main surface 3b of the multilayer film 3, which serves as a barrier layer, and is parallel to the xy plane. One side of the transparent electrode 12 parallel to the xy plane is in contact with the main surface 3b. Thus, the transparent electrode 12 is adjacent to the barrier layer on the main surface side of the silicon nitride film 5, which is the uppermost layer.

[0045] Examples of transparent electrodes 12 include films made of materials that are transparent and conductive, such as indium tin oxide (ITO), zinc oxide (ZnO), tin dioxide (SnO2), and fluorine-doped tin oxide (FTO).

[0046] The refractive index of the transparent electrode 12 is preferably greater than or equal to the maximum value of the refractive index in the barrier layer. Since the exit angle (β) is smaller than the incident angle (α) of light transmitted from the silicon nitride film 5 to the transparent electrode 12 at the interface between the barrier layer (multilayer film 3) and the transparent electrode 12, light is guided into the transparent electrode 12 when the direction of travel is nearly perpendicular to the main surfaces 3a and 3b of the multilayer film 3. Therefore, light entering the transparent electrode 12 from the main surface 3b of the multilayer film 3 converges and exits laterally in a direction more perpendicular to the main surface 3b. The refractive index of the transparent electrode 12 can, for example, be 1.7 or higher. According to one example, the refractive index of the transparent electrode 12 can be 2.0 or lower.

[0047] Figure 4 The transparent electrode-coated gas barrier film 8 shown exhibits excellent barrier performance against gases such as water vapor and oxygen. Furthermore, the gas barrier film 8 is visible light transmittant and can efficiently capture light.

[0048] Next, regarding Figure 5 The gas barrier membrane shown is explained below. Figure 5 The transparent electrode-supported gas barrier film 9 shown comprises a substrate 2, a multilayer film 3, a second layer 7, and a transparent electrode 12. Details of the substrate 2 and the multilayer film 3 are as follows... Figure 2 As explained in the text. Details of the second layer, 7, are as follows: Figure 3 As explained in the text. Details of the transparent electrode 12 are as follows: Figure 4 As explained in the text.

[0049] Figure 5 The transparent electrode-coated gas barrier film 9 shown exhibits excellent barrier performance against gases such as water vapor and oxygen. Furthermore, the gas barrier film 9 is visible light transmittant and can efficiently capture light. In addition, the gas barrier film 9 can suppress warping of the substrate 2.

[0050] While the application of the gas-barrier film of the first embodiment is not particularly limited, it is preferably used for applications requiring gas barrier properties against water vapor or oxygen. For example, the gas-barrier film of the first embodiment can be used in photoelectric conversion devices. Examples of photoelectric conversion devices include solar cell devices, light sensors, and optical storage devices.

[0051] The gas barrier film of the first embodiment described above includes a gas barrier layer, which comprises one or more multilayer films, each multilayer film including a light-transmitting first layer and an adjacent silicon nitride film. Furthermore, the refractive index of the gas barrier layer increases from one main surface side to the other. Therefore, the gas barrier film of the first embodiment has gas barrier properties and high light-taking performance.

[0052] (Second Implementation)

[0053] According to a second embodiment, a photoelectric conversion device is provided. This photoelectric conversion device includes the gas barrier film of the first embodiment. In addition to the gas barrier film, the photoelectric conversion device also includes a transparent first electrode, a second electrode, and a photoelectric conversion layer located between them. The first electrode is adjacent to the gas barrier layer on the main surface side where the silicon nitride film is located. This photoelectric conversion device can also be considered as having a gas barrier film with a transparent electrode as described in the first embodiment. That is, the first electrode corresponds to the transparent electrode described in the first embodiment. From this viewpoint, the photoelectric conversion device, in addition to having a gas barrier film including a transparent electrode, also includes a second electrode and a photoelectric conversion layer located between the transparent electrode and the second electrode.

[0054] The photoelectric conversion device can be, for example, a perovskite solar cell or other solar cell device. Besides solar cells, photoelectric conversion devices can also be light sensors, optical storage devices, etc.

[0055] As described with respect to the first embodiment, the gas barrier layer included in the above-described gas barrier film has a gradual change in refractive index that increases from one main surface side to the other. Therefore, the direction in which light passing through the gas barrier layer exits in the direction of increasing refractive index is closer to perpendicular to the exiting surface. Therefore, by aligning the main surface of the gas barrier layer with the photoelectric conversion layer at its maximum refractive index, the light acquisition efficiency of the photoelectric conversion device can be improved.

[0056] Reference Figure 6 and Figure 7 An example of applying the photoelectric conversion device of the embodiment to a solar cell device will be described. In each figure, the thickness direction of the solar cell device is parallel to the z-axis direction. The surface direction of the solar cell device is parallel to the plane defined by the x-axis and y-axis directions. The x-axis, y-axis, and z-axis directions intersect each other perpendicularly. Furthermore, in each figure, components that appear in multiple figures are labeled with the same reference numerals, and descriptions are omitted.

[0057] Figure 6 The solar cell device 20 shown includes a barrier film 1 as in the first embodiment, a transparent electrode 12 as the first electrode, a hole transport layer 13, a photoelectric conversion layer 14, an electron transport layer 15, a cathode 16 as the second electrode, an adhesive layer 17, and a backsheet 18. Details of the barrier film 1 and the transparent electrode 12 are as described in the first embodiment. The two surfaces of each of the transparent electrode 12, hole transport layer 13, photoelectric conversion layer 14, electron transport layer 15, and cathode 16 that intersect the thickness direction (z-axis direction) are called principal surfaces (main surfaces). Each surface is parallel to the xy plane. The transparent electrode 12 is disposed on the principal surface 3b of the multilayer film 3, which serves as the barrier layer of the barrier film 1, and is parallel to the xy plane. One surface of the transparent electrode 12 parallel to the xy plane is in contact with the principal surface 3b. Thus, the transparent electrode 12 (first electrode) is adjacent to the barrier layer on the principal surface side of the silicon nitride film 5, which is the uppermost layer. The stack of the barrier film 1 and the transparent electrode 12 can be considered as a barrier film 8 with a transparent electrode. A hole transport layer 13, a photoelectric conversion layer 14, an electron transport layer 15, and a cathode 16 are sequentially disposed on the other side of the transparent electrode 12 parallel to the xy plane. A back sheet 18 is fixed to the cathode 16 on the other side of the substrate 2 parallel to the xy plane via an adhesive layer 17. Sunlight or illumination light, for example, shines from the first direction 19 onto the other side 2b of the gas barrier film 1.

[0058] Examples of transparent electrodes 12 serving as the first electrode include films made of materials that are transparent and conductive, such as indium tin oxide (ITO), zinc oxide (ZnO), tin dioxide (SnO2), and fluorine-doped tin oxide (FTO).

[0059] The hole transport layer 13 has the function of blocking electrons generated in the photoelectric conversion layer 14 and selectively and efficiently transporting holes to the transparent electrode 12.

[0060] Examples of photoelectric conversion layer 14 include a perovskite layer. Examples of perovskite-type compounds include lead iodide methylammonium (CH3NH3PbI3).

[0061] The electron transport layer 15 has the function of blocking holes generated in the photoelectric conversion layer 14 and selectively and efficiently transporting electrons to the cathode 16.

[0062] The cathode 16, serving as the second electrode, is conductive and, depending on the circumstances, is made of a transparent material. Examples of cathode 16 include layers comprising Ti and / or Al.

[0063] In the solar cell device 20 with the above-described structure, light is irradiated, for example, from the first direction 19 towards the other side 2b of the substrate 2, which contains the gas barrier film 1 (or the transparent electrode gas barrier film 8). If the photoelectric conversion layer 14 absorbs the irradiated light, electrons and their paired holes are generated. For example, electrons are captured by the cathode 16 via the electron transport layer 15. Holes are captured by the transparent electrode 12 via the hole transport layer 13. Thus, a photoelectric conversion reaction occurs.

[0064] The gas barrier film 1 has high light capture efficiency from the first direction 19, enabling efficient transmission of light incident at various angles onto the other side 2b of the substrate 2 to the photoelectric conversion layer 14. As a result, the photoelectric conversion efficiency of the solar cell device 20 can be improved. Furthermore, the gas barrier film 1 has excellent barrier properties against gases such as water vapor and oxygen, thus suppressing the intrusion of gases into the solar cell device 20. As a result, the lifespan of the solar cell device can be extended.

[0065] The transparent electrode 12 preferably has a refractive index greater than or equal to the maximum refractive index in the gas barrier layer. By further extending the gradient of the refractive index in the gas barrier film rising from the other side 2b of the substrate 2 toward the photoelectric conversion layer 14 to the transparent electrode 12, the light extraction efficiency is further increased. The refractive index of the transparent electrode 12 can, for example, be 1.7 or higher. According to one example, the refractive index of the transparent electrode 12 can be 2.0 or lower.

[0066] Next, regarding Figure 7 The solar cell device 21 shown will be described below. Solar cell device 21 and reference... Figure 6 The difference in the described solar cell device 21 is that it includes the gas barrier film 6 of the first embodiment instead of the gas barrier film 1 of the first embodiment. Alternatively, the solar cell device 21 may also be described as including the transparent electrode gas barrier film 9 of the first embodiment instead of the transparent electrode gas barrier film 8 of the first embodiment. The details of the gas barrier film 6 (or the transparent electrode gas barrier film 9) are as described in the first embodiment. Except for the gas barrier film 6 (or the transparent electrode gas barrier film 9), the details of the solar cell device 21 are the same as those described in the reference. Figure 6 The solar cell device 20 described above is the same.

[0067] In the solar cell device 21 with the above-described structure, when light is irradiated from the first direction 19 toward the second layer 7 of the gas barrier film 6 (or the transparent electrode gas barrier film 9), a photoelectric conversion reaction occurs similarly to that of the solar cell device 20 described above. The gas barrier film 6 has high light capture efficiency from the first direction 19, enabling efficient transmission of light incident at various angles onto the other side 2b of the substrate 2 to the photoelectric conversion layer 14. As a result, the photoelectric conversion efficiency of the solar cell device 20 can be improved. Furthermore, the second layer 7 of the gas barrier film 6 can suppress warping of the substrate 2, thus preventing warping and other deformations in the solar cell device 21. In addition, the gas barrier film 6 has excellent barrier properties against gases such as water vapor and oxygen, thus suppressing the intrusion of gases into the solar cell device 21. As a result, the lifespan of the solar cell device can be extended.

[0068] In the example above, the first electrode (transparent electrode 12) is used as the anode and the second electrode as the cathode 16, but the configuration of these electrodes can also be reversed. That is, the first electrode (transparent electrode 12) can be the cathode and the second electrode can be the anode. In this case, the configurations of the hole transport layer 13 and the electron transport layer 15 are also interchanged.

[0069] Although no example is illustrated, a gas barrier film can also be provided on the second electrode side in addition to the first electrode side. The backsheet 18 is omitted; instead, the gas barrier film is overlapped on the second electrode. If a light-transmitting electrode, i.e., a transparent electrode, is used as the second electrode, light can also be captured from the second electrode side. Therefore, light can be received from both sides of the solar cell device. In this case, it is preferable that the refractive index of the second electrode is greater than or equal to the maximum refractive index of the portion of the silicon nitride film adjacent to the second electrode, i.e., greater than or equal to the maximum refractive index of the gas barrier layer. Similar to the first electrode side, there is an increase in refractive index from the outermost surface of the gas barrier film disposed on the second electrode toward the second electrode, thereby increasing the light capture efficiency.

[0070] As explained above, the photoelectric conversion device of the second embodiment has the gas barrier film of the first embodiment, thus suppressing the intrusion of gases such as water vapor and oxygen, and achieving high light capture efficiency. As a result, the photoelectric conversion device has a long lifespan and excellent photoelectric conversion efficiency.

[0071] Several embodiments of the present invention have been described, but these embodiments are merely illustrative and are not intended to limit the scope of the invention to these embodiments. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments or variations thereof are included in the scope or spirit of the invention, and are included within the scope of the invention described in the patent claims and their equivalents.

Claims

1. A gas barrier membrane, characterized in that, It includes a gas barrier layer, the gas barrier layer comprising one or more multilayer films, the multilayer films comprising a light-transmitting first layer and a silicon nitride film adjacent to the first layer. The first layer is located on one main surface of the gas barrier layer, and the silicon nitride film is located on the other main surface of the gas barrier layer. The refractive index of the gas barrier layer increases from the principal side where the first layer is located toward the other principal side.

2. The gas barrier membrane as described in claim 1, wherein, The minimum refractive index of the silicon nitride film is 1.54, and the maximum refractive index of the silicon nitride film is 1.

7.

3. The gas barrier membrane as described in claim 1, wherein, The refractive index of the gas barrier layer increases from 1.4 to 1.7 from the principal plane side where the first layer is located to the other principal plane side.

4. The gas barrier membrane according to any one of claims 1 to 3, wherein, The first layer is selected from the group consisting of organosilicon compound films, silicon oxide films, organic-inorganic mixed films, and organic films.

5. The gas barrier membrane according to any one of claims 1 to 3, wherein, It also includes a transparent electrode that is adjacent to the barrier layer on the other main surface side where the silicon nitride film is located, and the transparent electrode has a refractive index greater than or equal to the maximum value of the refractive index in the barrier layer.

6. A photoelectric conversion device, characterized in that, It comprises: a light-transmitting first electrode, a second electrode, a photoelectric conversion layer between the first electrode and the second electrode, and a gas-barrier film according to any one of claims 1 to 5. The first electrode is adjacent to the gas barrier layer on the other main surface side where the silicon nitride film is located.

7. A photoelectric conversion device, characterized in that, It comprises: the gas barrier film as described in claim 5, the second electrode, and the photoelectric conversion layer between the transparent electrode and the second electrode.

Images